Date: Fri, 26 Jul 2019 13:57:22 -0400
From: Alvaro Herrera <alvherre@2ndquadrant.com>
To: Yuri Niyazov <yuri@academia.edu>
Cc: Pgsql-admin <pgsql-admin@lists.postgresql.org>
Subject: Re: Figuring out the correct age of datfrozenxid
Message-ID: <20190726175722.GA7885@alvherre.pgsql>
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On 2019-Jul-25, Yuri Niyazov wrote:

> all the tables have a very reasonable age, but the database itself still
> has an age approaching two billion. So, what do we do now?

I think vacuuming any table will update the database age.  For instance,
try creating an empty table and do "vacuum freeze" on it.

> Were we wrong to truncate and drop this unneeded table without letting
> a vacuum on it finish?

That seems an appropriate measure to have taken  You just need to have
the system figure out that it's gone.

-- 
Álvaro Herrera                https://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services